Dynamic behaviour analysis and diagnostics of wind turbine gearbox

Abstract

In Wind turbines (WTs), the gearbox is the most vulnerable part due to the rotating components such as gears and bearings, which are prone to premature failure. The occurrence of faults in due course of operation under harsh conditions is the cause of these premature failures. Because of such premature failure, wind turbine gearboxes (WTGs) have the largest downtime compared to other components of the WTs. The economy of energy industries and, subsequently, the countries' economies are significantly impacted due to these extensive downtimes. Therefore, it is of utmost importance to understand the dynamic behaviour of the WTGs under healthy and faulty conditions and to perform the diagnostics of WTG to avoid these failures. This dissertation addresses the dynamic behaviour analysis of the WTG considering amplitude modulation (AM), gravity, variable speeds, and aerodynamic loads. This thesis also addresses a modalbased technique for damage detection in WTG. A basic dynamic model of a three-stage WTG is developed and modified to achieve different objectives. The dynamic model comprises two spur planetary stages and one spur parallel stage, representing a typical configuration of a modern WTG. A two-dimensional (2D) model of a planetary and parallel gear model is adopted from the well-established literature, and assembly is done employing a torsional coupling between the stages. The eigen value problem is formulated, and the modal parameters of the WTG are computed. The modes obtained from the current model are compared with modes found in the literature for a typical threestage WTG. It is concluded that the type of modes followed the same trend as found in the literature. The modal kinetic energy (MKE) and modal strain energy (MSE) distributions are also presented to analyze the most affected components of the WTG.